Docker for Mac OS X

This will be a set of questions and answers related to the Docker usage under OS X.

Where are my Docker files? They are supposed to be inside /var/lib/Docker but there is no such directory.

That's right Docker for Mac store all the data inside Virtual Machine which is located inside /Users/username/Library/Containers/com.docker.docker

The size of /Users/username/Library/Containers/com.docker.docker/Data directory is enormous 16GB+.

This is the normal behaviour because Docker for Mac doesn't implement TRIM to free unused space. You may find more details on Github. As for now the only working solution for me was resetting Docker (which means removing all images, containers and volumes).

Persistence in Docker for Mac.

You probably shouldn't use recommended Volumes API because it will store all your data inside Docker VM instead of your local file system. It means that when you make Docker reset (e.g. to free some space) you will loose your "persisted" data. As for now I think that the best (safest) option is staying with Data Volume Containers. As they will be normally backed up by your Time Machine backups.